The company tesa AG, Hamburg produces a dose-measurement film for electron-beam radiation. In this film, a radiation-sensitive layer of thickness 20 μm has been arranged on a polyester film of thickness 50 μm. The radiation-sensitive layer is in essence composed of a polyester lacquer and of the radiation-sensitive dye pararosaniline nitrile. To produce the measurement film, the constituents of the layer are mixed in a solvent and applied to the polyester film. The solvent is then in turn removed from the layer in a drier.
The radiation-induced color reaction of pararosaniline nitrile in the dosimeter foil is given below:

The radiation-sensitive dye pararosaniline present in the measurement film is transparent prior to irradiation. As radiation dose increases it assumes an increasingly strong red color, since green light with wavelength maximum of about 550 nm is absorbed by the dye.
The following relationship applies to transmittance of green light through the film:Tgr=Tgr0*e−(a*d+b*D*d) where    Tgr0=constant, about 0.88, since a portion of the incident light is reflected by the surface.    Tgr=transmittance of green light    a=radiation-independent absorption coefficient    d=thickness of radiation-sensitive layer    b=absorption coefficient which defines the radiation-sensitivity of the film    D=electron-beam radiation dose
For a measured transmittance, the electron-beam radiation dose received is therefore:
  D  =            -                        ln          ⁡                      (                                          T                                  g                  ⁢                                                                          ⁢                  r                                            /                              T                                  g                  ⁢                                                                          ⁢                  r                  ⁢                                                                          ⁢                  0                                                      )                                    b          *          d                      -          a      b      
From the formula it can be seen that thickness variations of the radiation-sensitive layer lead to measurement deviations of the same percentage magnitude. However, considerable cost is required to produce layer thicknesses of 20 μm with very small thickness deviations.
tesa AG therefore produces a second dose-measurement film for electron-beam radiation in which iron oxide is mixed into the radiation-sensitive layer. Prior to irradiation, the layer with iron oxide admixture has the same absorption coefficients a. for red and green light. Furthermore, the transmittance Trt for red light at about 650 nm is independent of the electron-beam radiation dose.
The transmittance Trt for red light is therefore used for thickness correction according to the relationship known to the person skilled in the art:Trt=Trt0*e−a*d 
The result for the electron-beam radiation dose D when the transmittance for green and red light is incorporated with the given precondition Trt0=Tgr0 is:
  D  =            (                                    ln            ⁡                          (                              T                rt                            )                                            ln            ⁡                          (                              T                                  g                  ⁢                                                                          ⁢                  r                                            )                                      -        1            )        *    b  
The company Polymer-Physik, Tübingen has produced a measurement device appropriate to the film, in which red and green light is generated via respectively a green light-emitting diode and a red light-emitting diode arranged alongside one another. The transmittances of the measurement film are measured via two photo transistors opposite to the light-emitting diodes. The device indicates the electron-beam radiation dose directly to the user in the conventional unit “kilogray” (kGy).
The dose-measurement film is mainly used for electron-beam systems in which material to be irradiated in the form of a web is run past an electron-beam source, and is suitable for electron-beam radiation doses of about 3 to 50 kGy.
There have hitherto been no dose-measurement films which have sufficient absolute accuracy for the calibration of UV sources, for determination of UV radiation doses on industrial UV systems. Operators of UV systems therefore in essence use flat electronic devices which are adhesive-bonded to the web running through the UV system. By way of example, the “Power Puck” dose-measurement device from the company IET, USA has a diameter of about 100 mm and a thickness of about 15 mm, and these measurement devices cannot therefore be run through UV systems in which the UV sources have been arranged over deflector rolls for the conveying of material in the form of a web.
Since no alternatives with sufficient accuracy are available here, a complicated method involving product features has to be used to operate quality assurance. Furthermore, conventional electrically operated UV sources lose about 20% of their intensity in the first 1000 operating hours and are susceptible to soiling. Analysis of the causes of variations in product quality is therefore difficult without UV dose measurements.
Another factor is that, by way of example, when the “Power Puck” described is used in systems for the conveying of materials in the form of a web the dose is determined about 15 mm above the web and not on the web itself, and moreover obliquely incident radiation is only inadequately detected by virtue of the measurement sensor geometry, the result being that considerable deviations can occur with respect to the radiation dose within the product.
The situation in the case of three-dimensional moldings run through UV systems is even more problematic. Here, it is practically impossible to achieve correct location-dependent determination of the dose on the surface of the moldings using a “Power Puck”.
The dose-measurement film from tesa AG described at an earlier stage above for electron-beam radiation assumes a red color when irradiated with UV light. However, its dependencies for UV radiation are not reproducible, and it cannot therefore be used for the UV-irradiation sector, which is of substantial commercial interest. In addition, the dye used, pararosaniline, is too sensitive for the UV dose range of interest. Furthermore, a thermally induced color change takes place above about 60° C. Radiation-induced heating in most UV polymerization systems and UV crosslinking systems exceeds that temperature.
The problem faced by the person skilled in the art in the light of this prior art is to provide a dose-measurement film which can detect not only electron-beam radiation but also UV radiation with sufficient measurement accuracy, in particular when the material to be irradiated is flexible. A further intention is to provide a corresponding dose-measurement method.